One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,11)(8,12)(9,10)(13,14)(15,20)(16,17)(18,19)(21,22,26,25)(23,28,27,24)(6,10)(11,12)(14,19)(15,17) involution — undirected(5,7,9,8)(6,11,10,12)(13,15,18,17)(14,20,19,16)(21,23)(22,24)(25,28)(26,27)(1,2)(3,4)(5,8,9,7)(6,12,10,11)(13,16)(14,15)(17,19)(18,20)(21,24,26,28)(22,27,25,23)(5,6)(7,11)(8,12)(9,10)(13,17,18,15)(14,16,19,20)(21,25,26,22)(23,28,27,24)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.